bcachefs: Fix snapshot deletion

Snapshots being deleted won't in general have a corresponding subvolume:
this fixes a spurious fsck error where we'd complain about a snapshot
pointing to a missing subvolume - but the subvolume had been deleted,
and the snapshot was pending deletion as well.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/subvolume.c b/fs/bcachefs/subvolume.c
index d74dc9843028dd0b85641c213fccc47c4e5dbfa1..083eb432458367e28315282aca4585c20a3569d0 100644 (file)
--- a/fs/bcachefs/subvolume.c
+++ b/fs/bcachefs/subvolume.c
@@ -17,7 +17,7 @@ void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c,
 {
        struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k);
 
-       prt_printf(out, "is_subvol %llu deleted %llu parent %u children %u %u subvol %u",
+       prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u",
               BCH_SNAPSHOT_SUBVOL(s.v),
               BCH_SNAPSHOT_DELETED(s.v),
               le32_to_cpu(s.v->parent),
@@ -196,18 +196,20 @@ static int bch2_snapshot_check(struct btree_trans *trans,
        u32 i, id;
        int ret;
 
-       id = le32_to_cpu(s.v->subvol);
-       ret = lockrestart_do(trans, bch2_subvolume_get(trans, id, 0, false, &subvol));
-       if (ret == -ENOENT)
-               bch_err(trans->c, "snapshot node %llu has nonexistent subvolume %u",
-                       s.k->p.offset, id);
-       if (ret)
-               return ret;
+       if (!BCH_SNAPSHOT_DELETED(s.v)) {
+               id = le32_to_cpu(s.v->subvol);
+               ret = lockrestart_do(trans, bch2_subvolume_get(trans, id, 0, false, &subvol));
+               if (ret == -ENOENT)
+                       bch_err(trans->c, "snapshot node %llu has nonexistent subvolume %u",
+                               s.k->p.offset, id);
+               if (ret)
+                       return ret;
 
-       if (BCH_SNAPSHOT_SUBVOL(s.v) != (le32_to_cpu(subvol.snapshot) == s.k->p.offset)) {
-               bch_err(trans->c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",
-                       s.k->p.offset);
-               return -EINVAL;
+               if (BCH_SNAPSHOT_SUBVOL(s.v) != (le32_to_cpu(subvol.snapshot) == s.k->p.offset)) {
+                       bch_err(trans->c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",
+                               s.k->p.offset);
+                       return -EINVAL;
+               }
        }
 
        id = le32_to_cpu(s.v->parent);
@@ -386,8 +388,10 @@ static int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
                goto err;
 
        bkey_reassemble(&s->k_i, k);
-
        SET_BCH_SNAPSHOT_DELETED(&s->v, true);
+       SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);
+       s->v.subvol = 0;
+
        ret = bch2_trans_update(trans, &iter, &s->k_i, 0);
        if (ret)
                goto err;
@@ -830,7 +834,6 @@ int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
        struct bkey_s_c k;
        struct bkey_s_c_subvolume subvol;
        struct btree_trans_commit_hook *h;
-       struct bkey_i *delete;
        u32 snapid;
        int ret = 0;
 
@@ -852,14 +855,7 @@ int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
        subvol = bkey_s_c_to_subvolume(k);
        snapid = le32_to_cpu(subvol.v->snapshot);
 
-       delete = bch2_trans_kmalloc(trans, sizeof(*delete));
-       ret = PTR_ERR_OR_ZERO(delete);
-       if (ret)
-               goto err;
-
-       bkey_init(&delete->k);
-       delete->k.p = iter.pos;
-       ret = bch2_trans_update(trans, &iter, delete, 0);
+       ret = bch2_btree_delete_at(trans, &iter, 0);
        if (ret)
                goto err;